| Two catalysts, modified skeletal Ni(S-Ni) and Pd/C, were prepared in this study. The structures, particle sizes, surfaces and components of catalysts were characterized using SEM, TEM, XRD, TG techniques. 3-Nitro-4-methoxyacetanilide(NMA) and nitro T-acid were selectively hydrogenated over the two catalysts.NMA was hydrogenated to 3-amino-4-methoxyacetanilide (AMA) with S-Ni as catalystin liquid phase. The effects of reaction conditions such as reaction pressure, reaction temperature, solvent, the amount of catalyst and concentration of substrate were studied and all of them were optimized to serve for industrial application. The product and the main by-product were identified by GC-MS. S-Ni showed high activity and excellent stability in either ethanol or methanol. The catalyst was repeatedly used for 43 times in ethanol, the conversion was kept at 100% and the selectivity of AMA was only decreased to 97.0% from 99.2%. The catalyst was used for 15 times in methanol, the conversion was kept at 100% and the selectivity of AMA was always higher than 99.5%.High dispersion of Pd/C was prepared using sol-gel method in which Pd nanoparticles were protected with surfactant and supported onto the active carbon. The activity of hydrogenation of nitro T-acid to T-acid was compared among 5wt%Ru/C, 5wt%Pd/C, 1wt%Pd/C, 5wt%Ru-Pd/C, Ru/S-Ni, 5wt%Pd/SiO2 and skeletal Cu 5wt%Pd/C and S-Ni was used as the catalysts for the reaction because of higher activity: the conversion of nitro T-acid with 5wt%Pd/C was kept at 98% after 33 times repeated use. The suitable reaction condition is as following: 3MPa, 110℃, and the concentration of nitro T-acid is 0.64 molL-1. The activity of Pd/C can be recovered by repeated supporting easily; the activity of S-Ni decreased little when used for 8 times at 130℃. The optimal conditions were: nitro T-acid=12g, water=40mL, θ=100℃,p=3.0～3.5MPa, catalyst=0.2～0.3g.
|
PDF Full Text Request